Re: [PATCH v1 03/11] drivers: soc: hisi: Add support for Hisilicon Djtag driver

From: Anurup M
Date: Fri Nov 11 2016 - 05:23:56 EST




On Thursday 10 November 2016 03:10 AM, Arnd Bergmann wrote:
On Wednesday, November 9, 2016 9:58:38 AM CET Anurup M wrote:
I also see that the compatible strings have the version included in
them, and you can probably drop them by requiring them only in the
fallback:

compatible = "hisilicon,hip05-cpu-djtag", "hisilicon,djtag-v1";
compatible = "hisilicon,hip05-io-djtag", "hisilicon,djtag-v1";
compatible = "hisilicon,hip06-cpu-djtag", "hisilicon,djtag-v1";
compatible = "hisilicon,hip06-io-djtag", "hisilicon,djtag-v2";
compatible = "hisilicon,hip07-cpu-djtag", "hisilicon,djtag-v2";
compatible = "hisilicon,hip07-io-djtag", "hisilicon,djtag-v2";

We want to have the first entry be as specific as possible, but
the last (second) entry is the one that can be used by the driver
for matching. When a future hip08/hip09/... chip uses an existing
interface, you then don't have to update the driver.
Thanks. I had a similar thought on this. So as I have the version string
in the
second entry "-v(1/2)".
I can use it in driver for matching. So i think I will change it as below.
Please correct me if my understanding is wrong.

static const struct of_device_id djtag_of_match[] = {
- /* for hip05(D02) cpu die */
- { .compatible = "hisilicon,hip05-cpu-djtag-v1",
+ /* for hisi djtag-v1 cpu die */
+ { .compatible = "hisilicon,hisi-cpu-djtag-v1",
.data = djtag_readwrite_v1 },
- /* for hip05(D02) io die */
- { .compatible = "hisilicon,hip05-io-djtag-v1",
+ /* for hisi djtag-v1 io die */
+ { .compatible = "hisilicon,hisi-io-djtag-v1",
From the code it looks like "hisilicon,hisi-io-djtag-v1" and
"hisilicon,hisi-cpu-djtag-v1" have the same register-level interface,
so we just need one compatible string for them to match the driver.

Arnd
The djtag versions in CPU die and IO die can be different in the same chip.
For example in hip06, the CPU die has djtag-v1 whereas IO die has djtag-v2.
So I think it need two different compatible string

for hip06 chip CPU DIE "hisilicon,hisi-cpu-djtag-v1"
for hip06 chip IO DIE "hisilicon,hisi-io-djtag-v2"

Thanks,
Anurup